diff --git a/CMakeLists.txt b/CMakeLists.txt
index a21563e33..ea554a5b0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -72,7 +72,7 @@ set(GIT_DIR "${PROJECT_SOURCE_DIR}/.git")
 if (EXISTS "${GIT_DIR}")
   # Try to make CMake configure depend on the current git HEAD so that
   # a re-configure is triggered when the HEAD changes.
-  add_git_dir_dependency("${PROJECT_SOURCE_DIR}" ADD_GIT_DEP_SUCCESS)
+  add_git_dir_dependency("${GIT_DIR}" ADD_GIT_DEP_SUCCESS)
   if (ADD_GIT_DEP_SUCCESS)
     if (Z3_INCLUDE_GIT_HASH)
       get_git_head_hash("${GIT_DIR}" Z3GITHASH)